Ozone has been long used to disinfect water and to oxidize residual organic matter and reduce mineral elements in water to be purified. The action of peroxides is also known, especially H.sub.2 O.sub.2, for eliminating odoriferous compounds, oxidizing the residual phenols in the water, or eliminating toxic products such as cyanide, chrome, etc.
Because some organic or mineral compounds are difficult to oxidize with either O.sub.3 or H.sub.2 O.sub.2 alone, for the past decade many authors have proposed combining the action of O.sub.3 with H.sub.2 O.sub.2 to achieve a substantial increase in the oxidation power of each of the two oxidizing agents considered individually. Indeed, it was found and proven that highly reactive hydroxyl radicals (OH) formed when the two oxidizing agents combine caused chain reactions causing the deterioration of the organic micropollutants to be greatly accelerated.
In the different technologies which have been described to date for this combined oxidation, it has been recommended that reactors be used, operating either statically and discontinuously (Glaze et al., Proceedings of the Second Intern. Conference, Edmonton, Alberta, Apr. 28-29 1987, pp. 233, 243; Namba & Nakayama, Bull Chem. Soc. Japan 55, pp. 3339-3340), or dynamically, i.e. with the water to be treated circulating continuously, but using a process in which the water circulates in a flow direction opposite to that of the oxidizing agents (Nakayama et al., Ozone, Science and Engineering, Vol. I, pp. 119, 131, 1979: D. W. Ferguson et al., Research and Technology, AWWA Journal, April 1990, pp. 181-191). It was proposed more recently to stagger in time and space hydrogen peroxide injections into an ozonization reactor in which the water to be treated is circulating, i.e. at different levels of the reactor Certificate of Addinir No. 88.17134 publ. 2640957 to French Patent No. 83,07764).